/*
 * Copyright (C) 2017-2019 Dremio Corporation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.dremio.exec.planner;

import java.util.Collection;

import org.apache.calcite.plan.RelOptPlanner;

/**
 * A callback that StoragePlugins can initialize to allow further configuration
 * of the Planner at initialization time. Examples could be to allow adding lattices,
 * materializations or additional traits to the planner that will be used in
 * planning.
 */
public abstract class PlannerCallback {

  /**
   * Method that will be called before a planner is used to further configure the planner.
   * @param planner The planner to be configured.
   */
  public abstract void initializePlanner(RelOptPlanner planner);

  public static PlannerCallback merge(Collection<PlannerCallback> callbacks){
    return new PlannerCallbackCollection(callbacks);
  }

  private static class PlannerCallbackCollection extends PlannerCallback{
    private Collection<PlannerCallback> callbacks;

    private PlannerCallbackCollection(Collection<PlannerCallback> callbacks){
      this.callbacks = callbacks;
    }

    @Override
    public void initializePlanner(RelOptPlanner planner) {
      for(PlannerCallback p : callbacks){
        p.initializePlanner(planner);
      }
    }


  }
}
